instrument cluster voltage limiter

inkjunkie

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what is its purpose in life? guessing that is there as sort of a step down device????
 

Poppabear

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It cuts the 12 volts down to 5 volts and than it dies, I think it was a very bad idea


:read2:
 

matthon

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I second that!
Do a search on this forum for more info, it has been covered a few times and there is good info out there.
 

6pk2goDemon

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what is its purpose in life? guessing that is there as sort of a step down device????

Send a PM to member "Redfish" or read his posts....8)

I still don't have a clue, but he does.
 

RonnyB

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It cuts the 12 volts down to 5 volts and than it dies, I think it was a very bad idea
I agree 100%!
I've always wondered why they didn't just use gauges that work with 12v.
It seems so logical...:dontknow:
Mine died by putting out a constant 12v and fried the gas and temp gauges.
Had to buy three instrument clusters just to get two working gauges. :cussing:

I know it was a dumb idea, because Ford did the same thing... :)
 

cudajim

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It's just a 5v. voltage regulator that can be replaced with a very common solid-state device which they didn't have back in those days.
 

RedFish

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In the beginning all vehicles had 6 volt charging systems and gauges.
When the 12 volt system came alone, mfgrs were faced with 2 options. Build 12 volt gauges or limit the power to 6 volts for the same gauges. 90 % opted for the 6 volt gauges and a voltage limiter. GM is one of the few who went to 12 volt gauges.
Those early 12 volt gauges produced almost constant needle movement.
 

player1up

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Red, one of these days my laziness is going to catch up to me ( I still have the factory limiter in the dash ) I even have a few of the 7805 ICs in the tool box for other misc projects and have yet to bring myself to pull the cluster......ugh just making excuses at this point :lol:
 

RonnyB

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In the beginning all vehicles had 6 volt charging systems and gauges.
When the 12 volt system came alone, mfgrs were faced with 2 options. Build 12 volt gauges or limit the power to 6 volts for the same gauges. 90 % opted for the 6 volt gauges and a voltage limiter. GM is one of the few who went to 12 volt gauges.
Those early 12 volt gauges produced almost constant needle movement.
Thanks, RedFish. That makes perfect sense. :)
They sure did wait a long time to design some 12v gauges. They must have used the same ones and just make different faces for newer cars. Wouldn't that mean you could take a 70s-era gauge and adapt it to a much earlier car? That would be pretty slick.

Why were the early 12v GM gauges so unstable?
 

70GT

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Here's a picture of my instrument cluster. I performed the solid-state mod, and it works much better.

100_1361.jpg


100_1362a.jpg
 

64dart170

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Here's a picture of my instrument cluster. I performed the solid-state mod, and it works much better.

:notworth:
Scematics Please!!!!
Wht are the values/componets used? Please advise!
Thanks!!:cheers:
 

dmoore

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37 Years Later Mine Still Works Great! But Your Very Correct...they Did Fail Back Then And Some Earlier Than Others....
 

RonnyB

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If you do the 7805 conversion, you should know that your gas and temp gauges will probably give low readings. That was causing me lots of confusion with my gas gauge. It was like my gas tank had shrunk. When the gauge read empty, I would fill the tank - but it would only take about 11 gallons or so.:dontknow: And I was only getting about 160 miles from a 'full' tank.

RedFish's reply explained what was happening.:thumbup: RedFish is officially 'The Man'!:notworth:

These gauges were originally designed for 6v systems, but with the 7805 mod, you are only giving them 5v. That's a 16% difference!

If the engineers who designed the gauges assumed the automotive electrical systems ran on a higher voltage (like 6.3v) and designed them accordingly, the difference will be even more. In my experience, electrical systems normally run a little higher than battery voltage.

I really like making little circuits like this 7805 one, because electronics is my business. But I've decided to bite the $50 bullet and buy one of the limiters from RT Engineering. It looks like a well-designed unit, and it won't stick on 12v like the original one did a few years ago and destroy my gauges. Replacing them was an expensive and frustrating scavenger hunt that I don't want to repeat.

I also don't want inaccurate gauges to be another of the quirks about the Dart that I have to think about. There are already more than enough! :)

It's a relief to finally know what was going on, but I'm a little disappointed that none of the sites giving the instructions for the project didn't mention this problem.

If my logic is wrong, please let me know. Sorry about the long post...
 

64dart170

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rp23g7

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I have been wondering about how to make mine work also, I always wondered how long did they use the limiter, and why they used it so long.

I gotta do that mod on mine, and possibly solder my wiring on the back of my instrument panel, as my limiter fried and burned the flat electical stuff.
 

1974stepside

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If you do the 7805 conversion, you should know that your gas and temp gauges will probably give low readings. That was causing me lots of confusion with my gas gauge. It was like my gas tank had shrunk. When the gauge read empty, I would fill the tank - but it would only take about 11 gallons or so.:dontknow: And I was only getting about 160 miles from a 'full' tank.

If my logic is wrong, please let me know. Sorry about the long post...

------------------------------------------------------------------------------------------------------------------------------------
I did the 7805 conversion then read your posting and orderred the solid state limiter. The problem I have is that when I was removing the cluster to get to the 7805 regulator it touched metal on the dash and shorted one of the tail lights, dash lights and guages (I know, I messed it up, im a noob).

I put in the solid state limiter and get the lights blinking behind it but do not know what to do. I replaced the tailight that blew but now I want the guages etc to work any ideas on how to proceed?

The tail lights, indicators, head lights, brake lights work. The dash lights, fuel, temp guages do not.
 

skykeith

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The early bi-metal type gauges were sensitive to voltage fluctuations. If the alternator was putting out 14v and you turned on lights/heater/wipers and the voltage dropped to 12v, the gauge would read differently. The IVR put out a constant 5v and the gauges were calibrated to 5v, so they would be unaffected by system voltage changes. The new air core type gauges have two opposing coils and are not affected by system voltage fluctuations, so there is no need for an IVR
 

dgc333

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FWIW, I did the 7805 upgrade in 2000 and it's worked flawlessly since. My oil pressure and water temp guages read higher after the swap than before and my fuel gauge didn't have a noticable change.

I hear complaints that the 7805 isn't rated for enough current. The 1A rating in these devices is without a heat sink, as long as you keep the internal junction temps within limits they can disapate a lot more power so use a heat sink. Also if you go to a place like Digi-Key there are 2.2 amp rated versions. There is also a 7806 wich is a 6 volt regulator if you feel you need the higher voltage.
 

ssaahemifan

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I was using the $6 radio shack IVR as outlined in MA for a long time.

Couple of gagues were a bit low, and slower to respond but the tradeoff's were worth it at the time

I've since switched it out to a RTE unit - with much better performance.

I hated to spend the extra $$ BUT once I realized that if there was a loss of ground with the Radio Shack version that it will default to 12V I didn't want the risk of fried guages.

something to consider.......
 

ic237

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I was using the $6 radio shack IVR as outlined in MA for a long time.

Couple of gagues were a bit low, and slower to respond but the tradeoff's were worth it at the time

I've since switched it out to a RTE unit - with much better performance.

I hated to spend the extra $$ BUT once I realized that if there was a loss of ground with the Radio Shack version that it will default to 12V I didn't want the risk of fried guages.

something to consider.......

Just an update, on ebay they are selling a regulator for 20 bucks. It comes with a no hassel warranty.

http://cgi.ebay.com/ebaymotors/ws/e...595327271&viewitem=&sspagename=STRK:MESELX:IT

 

glhx

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I'm bringing this back for a question.

I ran the 7805 set up years ago. Never drove the car much to see how. Accurate it was. I was just happy to have the gas gauge back working.

I ordered some 7805s. Should be here in a few days.
However......

I can get a 7806 6 volt output right now. What will this do?
Make the gauge more accurate?
or make the gauge and burn it out over time?
 

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